Mailing List Archive: MythTV: Commits

Ticket #7232: DVB scanning channels fails with error parsing parameters

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mythtv at cvs

Oct 3, 2009, 10:26 AM

Post #1 of 11 (717 views)
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Ticket #7232: DVB scanning channels fails with error parsing parameters

mythtv at cvs

Oct 3, 2009, 1:17 PM

Post #2 of 11 (692 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

#7232: DVB scanning channels fails with error parsing parameters
------------------------------------------------+---------------------------
Reporter: Tim Jordan <tim [at] wheresrover> | Owner: ijr
Type: defect | Status: new
Priority: minor | Milestone: unknown
Component: MythTV - General | Version: unknown
Severity: medium | Resolution:
Mlocked: 0 |
------------------------------------------------+---------------------------

Comment(by mythtv [at] dadeos):

I am experiencing the same problem.

I have identified the cause on my system to be problems with
{{{DTVTunerType::kTunerTypeUnknown}}} being defined as {{{0x8000000}}},
which gcc 4.3.3 wishes to represent as an unsigned value on my 32-bit
system. Commit #21935 attempted to resolve the signed/unsigned comparison
compiler warnings, however this change breaks comparisons with
{{{DTVTunerType::kTunerTypeUnknown}}} on my system. i.e. the code in
{{{ScanWizard::SetPage()}}} from {{{libs/libmythtv/scanwizard.cpp}}}

{{{
DTVTunerType parse_type = DTVTunerType::kTunerTypeUnknown;
if (parse_type != DTVTunerType::kTunerTypeUnknown)
{
// This code gets executed (which is wrong!!)
}
}}}

The attached patch resolves these problems by eliminating the comparison
operators from the {{{DTVTunerType}}} class.

The patch additionally removed the comparison operators from the
{{{DTVParamHelper}}} class, as they are unnecessary, and removes the need
for {{{DTVTunerType::initStr()}}} function, which was extremely
inefficient.

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7232#comment:1>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Oct 3, 2009, 1:31 PM

Post #3 of 11 (702 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

mythtv at cvs

Oct 3, 2009, 2:27 PM

Post #4 of 11 (691 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

mythtv at cvs

Oct 4, 2009, 11:59 AM

Post #5 of 11 (691 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

mythtv at cvs

Oct 4, 2009, 2:34 PM

Post #6 of 11 (694 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

#7232: DVB scanning channels fails with error parsing parameters
------------------------------------------------+---------------------------
Reporter: Tim Jordan <tim [at] wheresrover> | Owner: danielk
Type: defect | Status: infoneeded
Priority: minor | Milestone: 0.22
Component: MythTV - General | Version: head
Severity: medium | Resolution:
Mlocked: 0 |
------------------------------------------------+---------------------------

Comment(by mythtv [at] dadeos):

Yes, the {{{7232-v1.patch}}} also resolves the problem.

The problem appears to lie in the comparison that was being perform within
{{{DTVTunerType::operator!=()}}} reinterpret casting the {{{value}}}
member to be an unsigned int would be another solution.

It's slightly inaccurate to complain that gcc is treating the enumeration
inconsistently. The problems are caused by the fact that {{{0x80000000}}}
is an unsigned integer and as such is too large to fit within a signed
integer type. The code is incorrect, not the compiler.

It is better to compare objects of the same type, which is why I proposed
the solution I did.

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7232#comment:5>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Oct 4, 2009, 11:35 PM

Post #7 of 11 (692 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

mythtv at cvs

Oct 5, 2009, 9:02 AM

Post #8 of 11 (670 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

mythtv at cvs

Oct 5, 2009, 9:14 AM

Post #9 of 11 (670 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

#7232: DVB scanning channels fails with error parsing parameters
------------------------------------------------+---------------------------
Reporter: Tim Jordan <tim [at] wheresrover> | Owner: danielk
Type: defect | Status: closed
Priority: minor | Milestone: 0.22
Component: MythTV - General | Version: head
Severity: medium | Resolution: fixed
Mlocked: 0 |
------------------------------------------------+---------------------------

Comment(by danielk):

Peter, I think a reasonable interpretation of C++03, keeping C in mind,
will cause 0x80000000 to be treated as an 32 bit integer containing the
value 0x80000000. What I think happened is they added support for C++0x
which allows you to specify the underlying type of the enumeration. And
since the code was being rewritten the pre-existing logic which tried to
be compatible with C99 code and how enum's have traditionally been handled
was replaced with something quirky and less well thought out. Now whether
the MythTV code as written is incorrect depends on whether what the
compiler is doing now is in fact allowed by C++03; and I'm not sure after
staring at way too much of the spec. When I'm not sure that's generally a
good reason to avoid the code whether it really is correct or not.

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7232#comment:8>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Nov 14, 2009, 9:17 PM

Post #10 of 11 (552 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

mythtv at cvs

Nov 15, 2009, 12:49 AM

Post #11 of 11 (549 views)
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Re: Ticket #7232: DVB scanning channels fails with error parsing parameters [In reply to]

#7232: DVB scanning channels fails with error parsing parameters
------------------------------------------------+---------------------------
Reporter: Tim Jordan <tim@…> | Owner: danielk
Type: defect | Status: closed
Priority: minor | Milestone: 0.22
Component: MythTV - General | Version: head
Severity: medium | Resolution: fixed
Mlocked: 0 |
------------------------------------------------+---------------------------

Comment(by qupada@…):

I'm the other user referred to by anonymous. Running .22 r22824 on Gentoo
amd64, HDHR firmware 20091024.

Seeing these two packets repeated 8,000-13,000 times when beginning a
scan, after which mythtv-setup segfaults (tcpdump -iwlan0 -vv -s0 -A 'host
192.168.10.136')

15:22:36.916921 IP (tos 0x0, ttl 64, id 29588, offset 0, flags [DF], proto
TCP (6), length 82)
192.168.10.42.49891 > 192.168.10.136.65001: Flags [P.], cksum 0xfb83
(correct), seq 366375:366417, ack 287898, win 5840, length 42
E..Rs.@.@.1...
*..
.......qr.|..P.........."../tuner0/channel...qam:474000000...O.

15:22:36.917657 IP (tos 0x0, ttl 64, id 51255, offset 0, flags [none],
proto TCP (6), length 73)
192.168.10.136.65001 > 192.168.10.42.49891: Flags [P.], cksum 0x9db2
(correct), seq 287898:287931, ack 366417, win 1460, length 33
E..I.7..@..u..
...
*.....|....q.P.............ERROR: invalid channel.(.;)

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7232#comment:10>
MythTV <http://www.mythtv.org/>
MythTV
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